1/2.5+1/5.8+1/8.11+...+ 1/47.50 = ?
A=5/2.5+5/5.8+5/8.11+...+5/47.50
câu A 4/2.5+4/5.8+.....+4/47.50
tính S= \(\frac{1}{2.5}+\frac{1}{5.8}+\frac{1}{8.11}+....+\frac{1}{47.50}\)
Tính các tổng sau
a.6/2.5+6/5.8+6/8.11+...+6/44.47+6/47.50
b.1/9.11+1/11.13+...+1/41.43+1/43.45
4/2.5+4/5.8+4/8.11+...+4/62.65
B= 4/2.5 + 4/5.8 + 4/8.11 + 4/11.14
B=?
M= 4/2.5 + 4/5.8 + 4/8.11 + 4/11.14 + 4/14.17 + 4/17.20
Bài 7: A=\(\dfrac{4}{2.5}\)+\(\dfrac{4}{5.8}\)+\(\dfrac{4}{8.11}\)+...+\(\dfrac{4}{65.68}\)